# include <stdio.h>
int main (){
    int s, v, h, m, q;
    float t;
    scanf("%d %d", &s, &v);
    t = 470 - s*1.0/v;
    q = (int) t;
    if (q >= 0){
        h = q / 60;
        m = q % 60;
    }else{
        int p = 1440 + q;
        h = p / 60;
        m = p % 60;

    printf("%02d:%02d", h, m);
    return 0;
}